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FD: Wine Column January 14, 2009

Wine-making doesn’t halt in winter, but the pace is much slower

As bears hibernate, my garden is buried under a foot of snow, flowers and vegetables awaiting the warm spring sun.

The same is true in the cellars of most wineries.

In the expanses of a winery’s unheated barrel room, when winter arrives the ambient temperatures drop and fermentation slows.

Next spring, just as your gardens do, the yeasts will wake up and, if there’s any sugar left, get back to business of making alcohol.

However, most commercial wineries don’t have the luxury of waiting for Mother Nature to reawaken the yeast.

Particularly smaller wineries, where tank space is at a premium.

Parker Carlson has wine in his 1,500-gallon tanks, but if he wanted to hurry along that fermentation, he will have to heat the entire winery, which not only is prohibitively expensive but would affect wines in other tanks.

Carlson is content to let the wine make itself at its pace.

Eames Peterson, winemaker at Alfred Eames Cellars in Paonia, also lets nature takes its course. His barrels lie in a concrete cave, sleeping gently at around 55 degrees under 8 inches of reinforced concrete and 4 feet of earth.

Fermenting a red wine usually is smooth, starting almost as soon as the grapes are crushed, allowing yeasts to attack the sugar.

If things go right, the yeast converts all the sugar to the desired alcohol level without eating all the sugar first or succumbing to the alcohol.

Sometimes, you get a “stuck” fermentation, where the yeast no longer is converting sugar to alcohol.

You then have several options: Kick start the yeast by either raising the temperature of the wine, add some sort of yeast nutrients, or add another yeast that can live with higher alcohol levels.

Stuck fermentations are common, certainly no sign of deficiency on either the grapes or the winemaker, and commercial yeast manufacturers provide a specific “killer” yeast for when fermentation stops short.

Winemaker Nancy Janes at Whitewater Hill battled stuck fermentation this year and she took two steps to finish the fermentation.

“Usually, when the yeast runs out of sugar the wine is to the point it’s almost dry anyway, so to get the wine to continue we might add a little nutrient,” Janes said.

She also added a killer yeast, one that can survive up to 17 or 18 percent alcohol. That’s higher than what she wants for a finished wine, but there weren’t enough nutrients left to reach that level of alcohol.

“Normally, if we know the sugars are low (going into fermentation) we might add some nutrients,” Janes said.

Adding sugar to wine (a process called chaptalization after French chemist Jean-Antoine Chaptal) is illegal in many places, including California and Italy, but allowed where historically winemakers have had difficulty getting their grapes ripe (think France and certain parts of the United States).

That’s not the case in California, where winemakers get lush grapes and are more likely to add acid, which drops when sugar levels skyrocket.

Janes also helped the stuck fermentation resume by putting electric heaters near the wine tanks and covering it all with blankets.

“The winery was at 50–55 degrees, so we needed to raise the wine temperature a few degrees,” Janes said.

Winemakers relying solely on natural yeasts always keep an eye on fermentation, since you never really know what you’ll get with wild yeasts.

They can get fermentation going, but they might not be strong enough to continue once alcohol levels get above 7 or 8 percent, even if there is plenty of sugar left.

The syrah I’m making this winter with Sal Sassano is barely bubbling, but it doesn’t need much, since it’s already wine albeit a little too sweet for what we want.

His basement is about 54 degrees, and when you put your eye close to the glass carboys an occasional bubble will rise, a sign the yeast slowly continues to munch away.

“It’s almost there,” said Sal with evident satisfaction during a recent visit. “It’s just sleeping now. In the spring, it will be ready.”